This invention relates to tufting machines and more particularly to a method and apparatus for selectively forming cut pile and loop pile having substantially the same pile height as the cut pile in the same row of stitching in a backing fabric.
In U.S. Pat. of R. T. Card, No. 3,084,645, a method and apparatus for tufting cut pile and loop pile in the same row of stitching is disclosed. In spite of the enormous commercial success of that method and apparatus, and of the tufted product produced thereby, it has an inherent shortcoming that has limited it from even further success and acceptance of the tufted product produced. Because uncut loop pile is formed by backrobbing yarn from that loop to move a spring clip away from the point of the hook to allow the loop to be withdrawn from the hook while cut pile is not formed by backrobbing, it produces a tufted product having cut pile ends that project from the backing fabric more than the uncut loop pile. Thus, the pile height of the fabric produced is not level, but varies with the pattern. The cut pile has a greater pile height than the shorter uncut pile which appears less dense. This effect distracts from the appearance of the tufted product and has limited its appeal.
As pointed out in the aforesaid U.S. Pat. No. 3,084,645 there have been other, but commercially unsatisfactory, approaches for patterning a fabric selectively with cut pile and loop pile. In U.S. Pat. of McCutchen No. 2,879,728 selective loops on the hook are pushed off by a pattern controlled finger while others are allowed to stay on and are cut. Another proposal is illustrated in U.S. Pat. of McCutchen No. 2,879,729 wherein each needle has two opposed hooks associated therewith, one with a knife. When cut pile is desired a loop is transfered from the hook without the knife to the one with the knife. Although these proposals illustrate even level cut and loop pile their shortcomings are readily apparent; simplicity and reliability being primary concerns of the tufted fabric industry.
An effective approach to obtaining even level cut and loop pile is disclosed in U.S. Pat. No. 4,134,347 of Jolley et. al., assigned to the common assignee of the present invention, in which a pivotable gate member engagably cooperates with the bill of the hook to selectively open or close the passage from the bill to the hook blade of a seized loop. The loop is seized by the bill and the gate either allows or prevents a loop from moving beyond the bill to the closed end of the hook. Those loops that are allowed passage are cut, the other loops are shed by the bill. Setting of the stitches in the fabric draws both the cut and uncut loops to substantially the same level.